Freed W J, Dillon-Carter O, Kleinman J E
Preclinical Neurosciences Section, NIMH Neuroscience Center, St. Elizabeths, Washington, D.C. 20032.
Exp Neurol. 1993 May;121(1):48-56. doi: 10.1006/exnr.1993.1070.
[3H]AMPA binding, a measure of the non-NMDA excitatory amino acid receptors, was measured in the frontal cortex, caudate nucleus, and nucleus accumbens of postmortem human brain tissue samples. In normal human frontal cortex, the binding data were best fit by a two-site model, with Kd values of 137 nM and 11.3 microM, and Bmax values of 2780 fmol/mg protein and 67.6 pmol/mg protein, respectively. Binding was linearly related to protein concentration and was strongly inhibited by glutamic acid and quisqualic acid. Binding was partially inhibited by kainic acid and glutamic acid diethyl ester and only slightly inhibited by N-methyl-D-aspartic acid. AMPA binding was not inhibited by neuroleptic drugs, in vitro. Freezing and storage did not result in a loss of AMPA binding, and there tended to be an increase in AMPA binding with extended freezer storage. When tissue frozen intact was compared to tissue frozen as a homogenate, the high-affinity binding parameters were unchanged, but there was an increase in the affinity and Bmax of the low-affinity site for the tissue frozen intact. Thus it appears that only the high-affinity site can be measured accurately in tissue frozen intact. AMPA binding was not significantly altered by premortem neuroleptic administration, age, postmortem delay, or by moderate durations of freezer storage. No differences in AMPA binding were found in psychotic subjects compared to normal controls. There was, however, a pronounced increase in total AMPA binding in the caudate nucleus in subjects that had committed suicide.
采用[3H]AMPA结合法，对死后人类脑组织样本的额叶皮质、尾状核和伏隔核中的非NMDA兴奋性氨基酸受体进行了测定。在正常人类额叶皮质中，结合数据最适合用双位点模型拟合，其解离常数（Kd）值分别为137 nM和11.3 μM，最大结合容量（Bmax）值分别为2780 fmol/mg蛋白质和67.6 pmol/mg蛋白质。结合与蛋白质浓度呈线性相关，并受到谷氨酸和喹啉酸的强烈抑制。结合受到 kainic 酸和谷氨酸二乙酯的部分抑制，仅受到N-甲基-D-天冬氨酸的轻微抑制。在体外，抗精神病药物不会抑制AMPA结合。冷冻和储存不会导致AMPA结合丧失，并且随着冷冻储存时间延长，AMPA结合往往会增加。当将完整冷冻的组织与匀浆冷冻的组织进行比较时，高亲和力结合参数未发生变化，但完整冷冻组织的低亲和力位点的亲和力和Bmax增加。因此，似乎只有在完整冷冻的组织中才能准确测量高亲和力位点。生前给予抗精神病药物、年龄、死后延迟或适度的冷冻储存时间，均不会显著改变AMPA结合。与正常对照相比，精神病患者的AMPA结合未发现差异。然而，自杀患者的尾状核中总AMPA结合明显增加。
